STILLWATER, Okla. (AP)  Oklahoma State basketball player Tyrek Coger died from an enlarged heart after a 40-minute team workout on the football stadium stairs in hot weather, officials said Friday.

While the temperature was 99 degrees, it wasn’t known if the weather played a role in Coger’s death. The 22-year-old forward, who had recently transferred to OSU, did not appear struggle during Thursday’s workout at Boone Pickens Stadium, school spokesman Gary Shutt said at a news conference.

Coger sat down after the drills and the team noticed later he was having issues and called 911 about 5 p.m.; he was pronounced dead at a hospital at 6:23 p.m., Shutt said.

National Weather Service records show the temperature at 5 p.m. Thursday was 99 with humidity at 38 percent, causing a heat index of 106. The NCAA’s Sports Medicine Handbook does not provide specific guidelines for when teams should avoid practicing in extreme temperatures, but recommendations from the Centers for Disease Control and Prevention say sports teams should work outs in parts of the day when the heat isn’t severe.

“It was obviously hot yesterday, and you know, in competitive athletics, you’re always pushing,” athletic director Mike Holder said, adding that the team will thoroughly examine its practices following Coger’s death. “If you want to be great at something, you’ve got to push the envelope. That’s what conditioning is all about.”

Coger died from an enlarged heart  “cardiomegaly with left ventricular hypertrophy”  and the manner of death was natural, Oklahoma State Medical Examiner’s Office spokeswoman Amy Elliott said in an email Friday. The office’s family assistance coordinator, Eddie Johnson, told The Associated Press that the final report is not likely to be ready and released for another eight weeks.

Oklahoma State basketball coach Brad Underwood broke down Friday, noting that he was in Las Vegas on a recruiting trip when he learned of Coger’s death.

“This is the hardest couple of days I’ve ever experienced in my coaching life. You say goodbye to players when they graduate and that’s one thing,” Underwood said, pausing to wipe away tears with a towel. “Making that phone call to a mother is  there’s no words.”

The NCAA handbook says athletes should be gradually introduced to activity in warm temperatures over a “minimum period of 10 to 14 days.” Coger had been in Oklahoma since July 5, the school said. The handbook also provides a list of signs and symptoms of heat injury, notes that heatstroke is most likely to occur at the start of preseason practices and says some athletes with certain health conditions or who are not adequately in shape can be more susceptible to heatstroke.

It was not clear whether that was the case with Coger, whom Shutt said underwent health screenings to ensure he was physically able to participate in sports. Federal laws prohibit the school releasing those results.

The National Athletic Trainers’ Association said in guidelines published last year that when exertional heat stroke is suspected, the athlete should be plunged into cold water or, if that’s not available, covered in wet towels packed with ice. Oklahoma State officials said athletes were prepared to give Coger liquids after he went into distress.

The medical examiner’s email didn’t indicate whether Coger’s enlarged heart was an undiagnosed condition. But having an enlarged heart can create a propensity for problems and exercise, adrenaline and heat can make things worse, said Dr. Milind Desai, a cardiologist with the nonprofit Cleveland Clinic.

“The baseline disposition may already be there, but adding those factors can be like adding fuel to the fire,” Desai said. “These scenarios increase your chances of developing cardiac arrhythmias. He’s running and sweating, losing a lot of electrolytes, magnesium and potassium levels go haywire and they are all triggers for arrhythmias.”

In an interview with the Stillwater NewsPress published earlier this month, Coger spoke of frequent headaches during high school and said he had surgery several years ago to drain fluid from around his brain.

A native of Raleigh, North Carolina, Coger told the newspaper he recuperated before starting his college career at Eastern Florida State College. He transferred after one season to Cape Fear Community College in Wilmington, North Carolina, where he played last season. The 6-foot-8 player signed with Ole Miss last fall but opted for OSU after the Southeastern Conference ruled he was ineligible due to transfer rules.

CFCC coach Ryan Mantlo told the (Wilmington) Star-News that Coger had “put in so much hard work.”

“Everything he’s been through, it’s a shame that it had to happen this way, but he’s such a nice young man,” Mantlo said. “It’s just a tragedy.”

Holder said Oklahoma State’s workouts are left largely to the strength and conditioning staff, which was overseeing Thursday’s drills. “I’ve got a lot of confidence in our staff here,” Holder said.

NCAA rules allow basketball teams to meet eight hours a week during the summer  time that can be broken up as two hours on the court and six on strength and conditioning, or all eight on strength and conditioning.

The AP originally reported Coger was 21, based on an OSU news release, but Shutt deferred Friday to the university police report on the incident, which lists his date of birth as Dec. 20, 1993.

Coger’s death is the latest tragedy for OSU. Last fall, a driver crashed into a crowd at the homecoming parade, killing four spectators and wounding dozens. In 2011, women’s basketball coach Kurt Budke, assistant Miranda Serna and two others died in a plane crash in western Arkansas. And in 2001, 10 people died in a Colorado plane crash, including two men’s basketball players and six staff members.

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Associated Press writer Jill Bleed and Claudia Lauer in Little Rock, Arkansas, and Tim Talley in Oklahoma City contributed to this report.